Not bad, a good sketch; things to check are (when doing a final piece) going over and finalising eg. the ovular bulbs and erasing lines. I'm sure when you produce full things your shading is good; just be careful to make sure that the lines are parallel, especially considering it is a 3D simulating image .

To Start, that drawing of the assault frigit is great! I think you could definatly do the concept job!

I made a model of your Chaos Cammand Center. Here it is! Notice it looks kinda bland. Anyway the second one is another version with more detial. Dude, you can do anything you want! I know it's a pain to think up detail, but the more you put in, the better the model is going to look.